This invention is concerned with a die and method 5 for producing flanged metal container ends.
To achieve maximum material utilization at high manufacturing speed when producing flanged metal container ends, it is desirable and at times necessary to complete the end in a single stroke of a conventional single action type press. The accepted and widely used die design for this procedure involves a punch section and die section which blanks and forms the end in the upright position with a flange. In this upright position, the surface of the end that will become the outside of the container in is contact with the punch section of the tooling. After removal from the die, the container end is subjected to the secondary operations of segment curling and double seaming. In segment curling, the outside portion of the cut blank is curled inwardly. After placement on the container end the so-formed curled end is doubly folded inwardly by a double seaming operation to ensure a tight fit. When producing container ends in this manner two problems exist that are the result of the die configuration.
Firstly, a burr is formed on the outside corner of the cut surface of the blank which is undesirable since it has an adverse effect on the curling and seaming operations because of drag created as the burr moves through the tooling profiles used in curling and seaming.
Secondly, the uniformity of the flange length as it extends radially outward from the container end center is difficult to control due to the release of compressive pressure prior to the completion of the container end. The flange length sets the proper area of material necessary to produce the finished doubleseam when the end is affixed to the container body. It is well known that variations in flange length on container ends can result in leakage of the contained material in varying degrees.
The present invention, on the other hand, provides a unique die which when used in a conventional single action press, provides maximum material utilization while producing the container end in the inverted position leaving the blank cut edge burr on the inside corner of the cut surface. Further the die employs a draw ring in the die section which remains clamped to the flange area of the container end through the complete formation of the end thereby producing container ends having more uniform flange lengths.